My first encounter with Peter Wanless, chief executive of the UK's Big Lottery Fund, was a single tweet in early 2009, wishing me luck on a grant application I had flippantly posted that I was struggling with. By late 2011, we were heading to a punk gig in Camden market, celebrating my birthday over a few pints with friends.

Peter sits at the helm of the largest grant-giving body in the UK, but his Twitter feed doesn't for a moment give the impression he holds the high-and-mighty position his business card says he does. A somewhat unpredictable combination of cricket commentary, Elvis Costello-laced music playlists, and random ALL CAPS bursts when his son gets hold of dad's phone, are interspersed with occasional updates about the latest grant programme BIG has announced or delivered on.

And he engages. Happy to have a chat or answer questions from people who want to talk to him on Twitter about his work, or otherwise. Peter first started using Twitter in late 2008 when, on a good day, it was viewed suspiciously by most of his counterparts in other large foundations and government.

Twitter has opened a door to Peter, and by extension BIG, for thousands of stakeholders, many of whom may previously have seen the funder as a bit of an ivory tower. In turn, Peter makes clear Twitter opened his own doors to the world beyond his office in the City of London. "I really think of Twitter as a place to exchange views and learn a tremendous amount," he tells me.

Through a relatively open and honest online presence – particularly given the pressures on someone in his position to toe a strict line on all issues political – Peter has found a regular opportunity to engage directly with those whose only previous connections to BIG were half a dozen or so rungs down the organisational command chain. In other words, he can learn directly from the frontline, subverting some of the inevitable shortcomings of an established hierarchy, without leaving the meetings that fill so much of his days.

That said, he was also keen to remind me that social media will only go so far in engaging staff or stakeholders in how the organisation is run: "Only certain people will walk through your open door – for others, you need to leave your office if you want them to engage with what you do," he says. Essentially, if not used carefully, Twitter can simply amplify the voices which are already shouting the loudest, while others become more marginalised. So Peter makes sure to get out of the office and meet the people who receive support from BIG.

He is also very conscious of who he follows, wanting to ensure that he is not creating an echo chamber for his own views of the world, but is learning from some of the diversity that Twitter enables him to so easily explore.

Peter admits that his first forays into Twitter resembled the "broadcasting" motives that have pushed so many organisations to create accounts, telling the stories of grant recipients when the media was broadly disinterested in picking them up. "[I had] this sense of wanting to alert the world to the fact that there were these incredible people doing amazing things which it was a great privilege for us to be funding."

However in late 2009, when a British newspaper ran a hatchet-job on the funder, noting Peter had claimed £9,000 in travel expenses the previous year and had "found the time" for over 3,000 Tweets, it was Twitter that came to his defence. "Even before the press office had moved into position to develop a rebuttal," Peter recounted, "various people were tweeting: 'well thank goodness there's a chief executive who bothers to engage with us directly on social media and takes time to travel out and see what we're doing on the ground in our charities!'"

While our organisations go to great lengths to prepare themselves for the kinds of PR disasters that very occasionally pop up, thanks to an errant tweet or blog, we rarely think of social media as our first line of defence against a range of public attacks or criticisms.

Yet Peter's story demonstrates just that: the time he had spent on Twitter (and out on the road) had been more valuable in protecting the organisation's name than any number of "disaster response" spin doctors the Lottery could have hired in to try and undo the reputational damage of a national paper's smear campaign.

It also blurred the organisational lines of the past, as unpaid supporters unofficially became a part of the organisational response to the smear, demonstrating that a culture of openness isn't confined to the organisation's walls, but influences a wide range of stakeholders.

As the support rolled in, Peter thought for the first time: "Wow! This is very powerful!" It was at this point he started to use Twitter differently – engaging more, listening more, learning more – taking advantage of not only his steadily growing audience, but also the extensive learning pool of Twitter users that he was able to engage with.

Gradually, @PeterWanless and @BigLotteryFund both began "creating space for people to tell their own stories" opening the medium to sharing direct testimonials of people and groups they had helped to fund, rather than trying to tell others' stories through a singular, organisational voice.

While social media is still a "minority sport" at the BIG offices, Peter believes the tone and personality of the organisation are much more open and engaged than they once were. Twitter's informality has meant that far more interactions, inside and outside of the organisation have begun to feel, in Peter's words, more like an "exchange of equals", brushing traditionally professional behaviour aside, in the interests of nurturing better relationships.

While there are still people within BIG who feel organisational culture hasn't opened up as much as it could, the fact that Peter can hear those voices at all – and takes them seriously enough to tell me they exist – is an indication of how far things have come.

While he would likely deny that the growing openness at BIG was his own doing, Peter has clearly modelled a way of being and working that others have felt comfortable enough to adopt and run with themselves. In contrast to an infinite number of other institutions' change management exercises, which have likely produced a fraction of the results, Peter and so many other employees at BIG have just gotten more comfortable being themselves at work, and seen the effect spread, online and off.